Mechanical torque indicatoe



Oct. 29, l940 J. Hg NADEN MECHANICAL TORQUE INDICATR Filed Jan. 28, 1939 Patented 29, 1940 UNITED STATES4V PATENT oFFlcE l MECHANICAL 'PORQUE INDICATOR A James' Henry Naden, Hendon, London, England,

Lillina,

assignor to Precision London,.England, a British company 4 Application January 28, 1939, Serial No. 253,424

In Great Britain February 4, 1938 4 mima (ci. zes-1) invention relates to mechanical torque indicators and .is concerned with the'provision vof apparatus which is more particularly, although not exclusively, intended for indicating the torque ,l the engine becomes distorted with theconselo quent mechanical deteriorationof lthe engine.

It has been proposed to construct a mechanical torque indicator of the spring type as a couplingv unit for use betweenfawrench and a nut or bolta but the spring type construction does not oper- 2'5 are equally well in both directions, i. e., l: de-L signed to indicate the torque when a nut of right hand thread is applied, it will not indicate the torque required for the removal of the-nut or u for applying a nut of left hand thread. 25' An object of this invention is to provide a torque indicating device that may be used be.- tween a Spanner wrench and a nut to indicate the torque applied either in tightening or loosening a nut or bolt. An object\is to provide Aa. 30 torque indicating device in the form of a mechanical coupling unit for use betweena wrench and a nut or bolt, )the device having surfaces for en-v A gagement by the wrench and a stud for engaging the nut or a nut-engaging element, and indicat- 35 ing mechanism at the end of the device opposite the stud, whereby the wrench does not prevent Y a reading of the indicated torque. More specifically, an object is to provide a torque measuring devic'e including a sleeve having indicating o mechanism at its outer end, a hollow torque tube secured at its outer end tothe outer end of the sleeve, and having an inner end for application tothe cnut or othe' element that is to be turned',

and a rod extending through the tube and lse- 5 cured to its inner end, the, outer end of the rod being coupled to the indicating mechanism and the outer surface of the sleeve being Vshaped to receive a wrench or spanner. y These and other objects and advantageswill be 'apparent from the following specification when taken with the accompanying drawing in which: Figure 1 is a longitudinal sectional view of one example of torque indicatingapparatus in accordanceA with the invention, part of the apparatus having been broken away to facilitate the drawi118. and f l Figure 2 is a plan view showing the indicating scale of the apparatus.

Referring now to the drawing, it will Vbe seen 5 that the apparatus comprisesl a main torsion bar I, the lower end of which, as seen in Fig-ure '1, is shouldered. at 2 to form a projecting shank Q l. The latter is non-round in external shape -f and is intended to be engaged in the non-round 1Q cavity of a standard box-Spanner head. Standard box-Spanner heads are in common use in conjunction with wrench bars which t in the heads in the same manner as does-'the'portion I of the torsion bar I.

ay be.y for example, hexagonal. The portion l at its lower end has a part 4a of circular section, the purpose of'which will be referred to 20 more particularly herina'fter. The upper end of the bar I has a portion 5 which is also nonround and which may be hexagonal. Between its ends the bar I maybe of circular reduced section as indicated in the drawing. 25'

-f The bar I is surrounded over the greater part of its length by a sleeve 6 which is in section hexagonal or otherwisenon-circular depending upon the external surface of the portions l and I of thebar I. The portion I of the bar I nts-3c closely within the sleeve'V and is anchored thereto with the aidvof a locking screw l'. The latter vserves mainly as a locating pin, since the engaging peripheral surface of the portion 5 and the inner surface' of the sleeve 8 are both hon-round 35 andare complementals As indicated, fboth the imaging surfaces in question may appear as hexagons in section. Thus, when the bar I is in position within the sleeve 8 any relative an g ular movement between the portion Il and the contig- 40' uousfpart of the sleeve i is substantially prevented. The lower end 8 of the sleeve t machined out so as to present. an internal annular `surface to form a bearing to accommodate the circular portion 4a of the bar I. In this manner 4,5 the sleeve i at its lower end provides a for the portion la at the lower end of the bar I.

At ita'upper end the sleeve 8 isl screwthreaded as at S and has a circular casing III screwed upon it. The locking screw I serves also to hold 5o l the casing Il in a definite position uponthe scre I of the sleeve l. The casing Il houses e actual indicating'mechanism of thel indicating device and such Amechanism is operated from a rodII whichpasses through f'f i.

Above the shoulder 2. l5 .there is a portion l of the bar I which is also 3f non-round exterior appearance and which the centre of the barA I. 'Ihe bar I is for the purpose formed `with a hollow I2, being bushed at I 3 at its lower end to receive flxedly the lower end of the rod II. the upper end of the internal bore I2, this latter bush serving only to provide a bearing for the rod II. The rod II projects at its upper end from the top of the bar Iand has a square section I5 which is reduced to a circular section pin I8. The square sectionl Il carries a rack arm I1, the rack teeth of which mesh with a pinion I8 which is fast upon a pin Il journalled at one end in the material of the casing III. 'I'h'e pin I 9 also carries xedly a further arm 20, the rack teeth of which engage a pinion 2I which is secured upon a sleeve 22. The latter is freely turnable about the pin I6 and carries a pointer 22. The

indicating mechanism described, ci-.ncr than the t pointer 22, is covered by a plate 24 which. incidentally, bears one end of the pin I9. The upper side of the casing I 2 has a glass window 2i to permit the pointer 22 torbe observed in conjuncplaced on the shank 2 in the same way that these' heads are used in connection with wrenches. The head is then placed over the nut that is to be tightened and.l a spanner is applied to the exterior of the sleeve 2, which has already been explained to be preferably hexagonal. A torque is exerted upon the sleeve 6 with the aid of a Spanner such torque being transnitted to the top of the sleeve and thence to the top portion 5 of the torsion ,bar I. The other end of the torsion bar I is eii'ectively connected with the nut that is being tightened, and said nut receives a working torque through the torsion bar I. According to the magnitude of theptorquethat itv transmits,

the icrsicn bnr i win undergo tcrsicnai deflection. It will be observed. that the rod II is secured to the4 torsion bar I only at the lower end? of the latter. Thus, the top end of the rod II will have a relative movement with respect to the top end of the torsion bar Independing upon the extentof the vtorsional deection experienced between the ends of the bar I. The casing I0 carrying the scale formed on the plate 24 is. anchored to the upper end of the torsion bar I. Hence there is a relative movement between the pointer 22 and the scale 24 to an extent proportional to the torsional deflection experienced by the bar I. Actually. the movement of the pointer 22 will be magnied according to the gear ratio in the transmission from the portion Il of the to the actual driving centre of the pointer orl needle 22. According to the direction in which the torque is transmitted to the nut, so the pointer moves clockwise or anti-clockwise over its associated scale.

Asl will be appreciated several modifications There is also a bush I4 at' would have the advantage that it could at once be seen to what extent a torque has been applied in the tightening of a nut. The dead pointer could also be used for simplicity of working, so that the latter could be set before using the apparatus, and the live pointer 22 then brought round until it coincides in its reading on the scale with the setting of the dead pointer.

'I'he hexagonal surface of the portion 4 of the bar I is made of such dimensions that it does -not nt closely within the hexagonal hollow of thesleeve 2. In thisway a predetermined extent of movement of the bar I in relation to the sleeve I is allowed, but there is a denite positive limit to such relative movement, the limit being dened by contact of the hexagonal portion 4 with the ats of the hexagonal internal surface of the sleeve B.

Other 'constructional modifications may be made. Thus, it maybe found desirable to modify the actual form of the torsion bar I. In ,the description above it has been stated that the portion I of the torsion bar has an external shape which may be hexagonal in order to fit into they hexagonal hollow of the sleeve 6. In practice thevbroachin'g that may be necessary in order to produce the ilt of the one element into the other may be found unwarranted e nse. In this case. both members could be mac ned out circular and a shear pin employed, which shear pin occupies an aperture indicated at X in dotted linesin Figure 1. By `correct proportloning of the shear pin C` a sumcient resistance could be obtained to allow of the construction indicated. The lower portion 4 of the torsion bar I may also be modiiled in several ways in order to obtain the 'desired limit effect and thereby to limit the twisting movement of the bar relative to the enclosing sleeveN i lWhat I claim and desire. to secure by Letters Patent of the United States is:

1. A. torque indicating device comprising a sleeve having between the inner and outer ends thereof externalv surfaces for rece ving a spanner, a torque member within said sleeve and having its outer end secured to the outer end of the sleeve, theother end of said torque member ex.

vingV a scale plate secured to the outer end of said sleeve beyond the spanner-r'eceiving yexternal surfaces there'of and a pointerI coupled to the inner 'end of said'torque member.

2. A torque indicating device as claimed in Aclaim 1, wherein said torque member is a torque tube, and a rod extends through said tube and has its inner end secured'to the inner end of the torque tube, the outer end of the rod being connected'to said pointer to actuate the same.

3. Apparatus for indicating the torque that is applied'to an object comprising a hollow torsion bar one end of which is adapted to be applied to the object, a sleeve-co-axial with the torsion bar and fixed to the end thereof removed from the object, sleeve having faces adapted to receive the normal wrench 'or spanner ofthe user, a rod disposed; centrally of the hollow torsion bar and xed to the end thereof adapted to be applied to the object. gearing operated by the relative rotation betweenthe rod and the sleeve, a needle or pointer operated by such gearing, and a calibrated dial disposed close to the needle to give reading of such relative rotation.

4. Apparatus for indicating the torque that is applied to an object comprising a hollowtorsion bar one end of which is adapted to be applied tov ilxed to the end thereof adapted to be applied tothe object, gearing operated by the relative rota- -tion between the rod andthe sleeve, a needle or pointer operated by such gearing, and a calibrated dial disposed close to the needle to give reading of such relative grotation; and stops whereby relative rotation between the torsion bar and the sleeve is prevented after a predetermined amount of deilection of the torsion bar.

JAMES HENRY NADEN. 

